Covid-19: on the trail of patients “incubators” of variants

The lack of resources allocated to HIV treatment in Nelson Mandela Bay, a metropolis located in the Eastern Cape Province, South Africa, may well have created the breeding ground for the emergence of the Beta variant of SARS-CoV- 2, recognized as a concern by the World Health Organization. This is the teaching of a study published in the journal Science, on September 9, and relating to the analysis of 8,746 Covid-19 genomes collected in 33 African countries.

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“Nelson Mandela Bay is among the regions in the world with the highest concentration of people both infected with HIV and deprived of appropriate treatment. The proportion of people effectively treated there is lower than in any other region of South Africa ”, denounces the bioinformatician Darren Martin, of the University of Cape Town, in South Africa, one of the authors of the study. “If these people are not taken care of as they should be by the government to ensure both access to treatment and its proper administration, then it is dangerous not only for themselves, but also for the rest of the world “, he warns. Infected people could indeed serve as “incubators” for variants, the persistence of the virus in their organism favoring the selection of potentially deleterious mutations.

“What we are finding is that if someone is treated properly for their HIV infection, the response to the coronavirus is comparable to that of a person who is not infected. But in the absence of treatment, the state of immunosuppression resulting from the HIV infection prevents the elimination of Covid-19 and the infection can last for several months ”, explains Alex Sigal, from the African Institute for Health Research in Durban, South Africa. “The hypothesis is that this Beta variant is an immune system escape variant”, he adds.

Antibody pressure

As its name suggests, an escape variant evades the neutralizing power of antibodies. Two conditions must be met for it to emerge, a high rate of multiplication of the virus, favoring the random appearance of mutations, and the existence of one or more factors in the environment exerting pressure on this heterogeneous viral population. Selection. In immunocompromised people, this pressure comes from antibodies against Covid-19. Their quantity is insufficient to eliminate the virus whose population diversifies as it replicates. Among the mutations thus occurring, some affect the molecular configuration of the regions of the virus targeted by the antibodies, weakening or canceling their neutralizing power. The variants which carry them thus escape the pressure exerted by the antibodies, taking an advantage within the viral population.

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Covid-19: on the trail of patients “incubators” of variants